Field of the Invention
The present invention relates to a core of a motor. More particularly, the present invention relates to a laminated core for a motor which can maintain squareness of the laminated core and increase a binding force of each core, thereby maximizing efficiency of the motor.
Background Art
In general, a motor includes a rotor and a stator. The rotor or the stator uses a core made of a conductive metallic material in order to form a necessary magnetic field. Moreover, laminated cores manufactured by laminating of a plurality of thin steel sheets.
Such a laminated core can show good performance of the motor when each sheet of the core must be laminated while accurately keeping verticality and firmly combined with another sheet of the core. In detail, if the core is laminated without maintaining verticality, namely, if squareness is not maintained, because an air gap which is a space between the rotor and the stator is not uniform, the rotor shows uneven rotation and is deteriorated in efficiency.
There are various attempts to combine the sheets of the core. In Japanese Patent Laid-open No. 06-086487, sheets of a core are combined by being welded perpendicularly in a state where each sheet of the core is stacked on another. In another way, Japanese Patent Laid-open No. 2010-130824 discloses a method for combining sheets of a core by caulking to pressurize stacked a predetermined position of the stacked sheets of the core by press die.
In a case of laser welding, squareness must be first secured, and then, laser welding is applied. However, caulking is carried out whenever each sheet of the core is stacked, and hence, caulking is widely used because it is effective in keeping squareness. However, the caulking according to prior arts has a disadvantage in that it does not secure bonding force at connected parts of split cores. There is a method to additionally weld only the connected parts of the split cores or to use a bonding member to the connected parts, but it increases manufacturing expenses because of additional process.
Therefore, the inventors of the present invention propose a laminated core for a motor with a new structure and a method for manufacturing the same.